My tranny is shot in my 03 civic (main shaft bearing) just bought a tranny from a junk yard does anyone know where i can find a DIY on how to do the swap?

 

take out the axles and starter. unbolt the trans and trans mount. drop the trans. reverse process for install.

 

It looks like one of the pictures is missing, but it should still be helpful. (it's also in the FAQ's)
https://honda-tech.com/forums/honda-civic-2001-2005-78/help-clutch-install-2254415/

 

That works well but its not 100% accurate, if you want to completely remove the sub frame you will need to remove your exhaust pipe from the flange under the catalytic converter (the exhaust runs under the sub frame on the back, as in between the subfram and the ground). However this is not require to remove the tranny, you only need to drop the sub fram on the front enough to get the tranny out, be sure to support the back of the frame so it doesnt rest on your exhaust if your not interested in removing it.
I just replaced my clutch and ISB in the tranny last weekend and thats what we did, worked just fine.